Pipelines used for oil and gas production may be formed from lengths of solid steel pipe welded together. Such pipelines can be handled using apparatus which grips the pipe externally, or internally. In each case a tool is urged into contact with a surface of the pipe. The strength of the pipe is such that a sufficient force can be applied by the tool so that static friction between the pipe and the tool enables the tool to be used to lift a significant mass of pipe. In the case of a pipeline being recovered from the sea bed this may be several hundred tonnes.
An alternative to the use of relatively rigid solid steel pipe is so called flexible pipe. This are used in applications where a pipeline will be subject to significant movement, such as in the case of risers running from the sea bed to a production platform. This flexible pipe is formed of multiple metal and polymer layers, and typically includes multiple layers of parallel helically wound steel strands with a polymer liner and sheath. Such pipe is significantly more flexible than solid steel pipe and so more resistant to fatigue in use. However, this flexibility renders the pipe difficult to handle using conventional tools. Owing to its flexibility it is not possible for conventional tools to grip either the outside or inside surface of the pipe with sufficient force to enable a significant mass of pipe to be lifted, because the pipe flexes under the application of pressure limiting the amount of friction which can be achieved between tool and pipe. Consequently, conventional pipe handling tools intended for use with solid steel pipe can only reliably lift flexible pipe with a mass in the order of tens, rather than hundreds, of tonnes making it unsuitable for pipeline recovery operations.
Embodiments of the present invention seek to address this problem.